Corrosion of metal structures, e.g., steel structures, embedded in substrates, e.g., of concrete, for re-enforcing the substrates for use, e.g., as highway bridge infrastructure, building structures, etc, is a problem. Coatings have been developed for the reduction of corrosion of the embedded metal structures. These coatings are typically applied as liquids to an external surface of a substrate in which the metal is embedded. The liquid applied coatings act to provide galvanic protection to the embedded metal.
The liquid coating typically includes two or more metals, such as magnesium and zinc, dispersed in a liquid coating vehicle, such as an inorganic silicate, where the two or more metals remain conductive after the coating dries. In operation, electrical connectivity between the coating and the embedded metal structures induces an electrical current that provides cathodic protection to the embedded metal structures with the coating acting as a sacrificial anode. The coatings are normally applied using methods similar to standard paints, e.g., brushing, rolling or spraying.
The coatings are often formed by dry mixing powders of the two or more metals together and then adding them to the coating vehicle. However, this can produce an inhomogeneous mixture of the two or more metal powders that when applied to a surface, results in inhomogeneous electrical connectivity between the coating and the embedded metal structures.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for alternatives to existing coatings for reducing corrosion of metal structures embedded in substrates.